Coiled tube blowout process and apparatus

ABSTRACT

A PROCESS AND APPARATUS FOR REMOVING THE INTERNAL SCARF FROM WITHIN A COIL OF WELDED TUBING HAVING A PLURALITY OF WRAPS WHICH COMPRISES FILLING THETUBING WITH A SUBSTANTIALLY NONCOMPRESSIBLE LIQUID AND APPLYING AGAS UNDER PRESSURE TO FORCE THE LIQUID AND SCRAF OUT OF THE TUBING. A PLUG IS NORMALLY PROVIDED INTERMEDIATE THE GAS AND THE LIQUID. THE PLUG TRAVERSES THE WRAPS OF THE TUBING   TO FORCE THE LIQUID AND SCARF OUT. A SECOND PLUG MAY BE PROVIDED AT THE OUTLET END OF THE TUBING.

July 23, 1974 RE|LLY 3,825,443

COILED TUBE BLOWOUT PROCESS AND APPARATUS Filed June 7, 1972 UnitedStates Patent 3,825,443 COILED TUBE BLOWOUT PROCESS AND APPARATUS DennisE. Reilly, Bellefontaine Neighbors, Mo., assignor to Olin CorporationFiled June 7, 1972, Ser. No. 260,405 Int. Cl. B08b 9/00 US. Cl. 13424 17Claims ABSTRACT OF THE DISCLOSURE A process and apparatus for removingthe internal scarf from within a coil of welded tubing having aplurality of wraps which comprises filling the tubing with asubstantially noncompressible liquid and applying a gas under pressureto force the liquid and scarf out of the tubing. A plug is normallyprovided intermediate the gas and the liquid. The plug traverses thewraps of the tubing to force the liquid and scarf out. A second plug maybe provided at the outlet end of the tubing.

BACKGROUND OF THE INVENTION This invention deals with an improved methodand apparatus for removing the internal scarf and other foreign matterfrom the inside of long lengths of coiled tubing. Normally in acommercial operation the inside of coiled tubing must be cleaned priorto shipment to a customer for use. This is particularly true withrespect to tubing made by welding an elongated strip.

It is conventional to remove the weld head on the inside of the tubing,thereby leaving an internal scarf within the tubing. For straightlengths of tubing, removal of this internal scarf can usually be easilyaccomplished by using a blast of compressed air.

However, to remove the internal scarf from a long length of coiledtubing such that the tubing would be usable in the longest manufacturedlength, the use of an air blast or similar means to remove the scarf isnot very effective and causes bunching and wadding of the internal scarfrequiring several blowing operations to force the scarf out of the tube,and sometimes it is impossible to blow the scarf out.

SUMMARY OF THE INVENTION In accordance with the present invention, ithas been found that the problem of removing the internal scarf and otherforeign matter from long lengths of coiled tubing can be substantiallyeliminated by first filling the tubing with a substantiallynon-compressible liquid such as water and then providing a plug at leastat the inlet end of the coil followed by the application of acompressible gas at a relatively high pressure to the inlet end of thecoil.

The substantially non-compressible liquid acts like a cylinder or ram asit moves though the coiled tubing and carries with it all the internalscarf and foreign matter which is contained within the liquid cylinder.The cylinder of liquid is moved by the action of the gas upon the plugwhich forces the plug and, therefore, the liquid through the coiledtubing.

The advantage of the process in accordance with this invention is thefact that the internal scarf moves with the liquid out of the exit endof the coiled tube without substantial bunching up or wadding whichcould form a blockage.

The apparatus in accordance with this invention includes means forfilling the coiled tube with a substantial non-compressible liquid,plugs positioned within at least the inlet end of the coiled tube andmeans communicating with the inlet end of the coiled tube for applying agas under pressure.

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Accordingly, it is a principal object of this invention to provide aprocess for removing the internal scarf and foreign matter from coiledwelded tubing particularly long lengths of such tubing.

It is a further object of this invention to provide an apparatus forcarrying out the aforenoted process.

Other objects and advantages will become apparent to those skilled inthe art as a detailed description follows with reference to thedrawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows in perspective a typicalcoiled tube to which this invention is applicable.

FIG. 2 shows sections of the coiled tube at each end of the coil afterthe tube has been filled with a substantially non-compressible liquidbut before the application of the gas under pressure.

FIG. 3 shows a perspective view of a typical plug in accordance withthis invention.

FIG. 4 shows a cross section of the coiled tube at each respective endduring the blow out procedure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS This invention isdirected to a method and apparatus for removing the scarfed weld beadand other foreign matter from within long lengths of coiled weldedtubing. The welded tubing in accordance with this invention is usuallyformed from metal strip which is shaped into the form of a tube followedby welding together of the strip edges.

Typical examples of prior art welding processes are set forth in US.Pat. Nos. 3,037,105, granted May 29, 1962; 2,794,108, granted May 28,1957; and 2,818,488, granted Dec. 31, 1957. The aforenoted patents setforth methods of high frequency forge welding metal strip into tubing;however, this is not meant to be limitive of the invention and othermethods of welding could be employed.

Apparatuses are also known in the art for removal of the weld bead onthe inside surface of the tube. One specific example, not meant to belimitive of the invention, is set forth in US. Pat. No. 3,349,212,granted Oct. 24, 1967.

The weld bead which is removed from the inside surface of the tube isknown in the art as scarf and generally travels along within the tubingafter its removal and stays within it during coiling.

It is desirable for manufacturing economy to weld extremely long lengthsof tubing. This is usually accomplished by coiling the welded tubingbecause of space limitations in the manufacturing facility and otherreasons. The coiled tubing contains within it the scarf as aforenotedand this internal scarf and other foreign matter generally must beremoved prior to redrawing and/or annealing or other further processing.

For straight lengths of tubing, the use of an air blast has been foundto be effective to remove the scarf from the inside of the tube. See forexample application Ser. No. 167,637, by D. T. Van Allman et al., filedJuly 30, 1971 and assigned to the assignee of the instant invention.

With long lengths of tubing in the form of a coil, however, an air blastis not an efiicient method for removing the internal scarf and otherforeign matter from within the coiled tubing. The use of an air blastsubjects the internal scarf to bunching and wadding which makes itdifiicult to remove. It usually requires several blowing operations toforce the scarf out if possible at all.

In accordance with this invention, the problems of the prior artprocesses have been overcome by first filling the coiled tubing with asubstantially non-compressible liquid.

The use of a non-compressible liquid acts like a cylinder or ram when itis forced to move through and out of the tubing and thereby it carrieswith it substantially all the internal scarf and foreign matter which iscontained within this cylinder of liquid. The cylinder of liquid isforced through and out of the tubing by means of a gas under pressurewhich is applied to a plug which is inserted at the inlet end of thecoiled tubing. The plug has a diameter substantially the same as theinside diameter of the tubing or slightly less than the inside diameter.The plug will be described in more detail hereinafter.

The gas under pressure may continue to be applied to the coiled tubingafter the plug has exited in order to remove any residual water or otherliquid.

Referring to FIG. 1 and 2, there is shown schematically a typical coilof tubing 1 in accordance with this invention. The coil 1 can besupported by a cart C as shown or in any other desired manner. Further,the coil 1 may be disposed with the wraps vertical or horizontal or asotherwise desired. The coiled tubing 1 is filled from the inlet end 2with water or other substantially non-compressible liquid 3. Any fluidpressure suificient to force the liquid 3 to flow around the wraps 4 ofthe coiled tubing 1 and out of the exit end 5 may be employed up to theburst pressure of the tubing. Pressures of to p.s.i. have been found tobe adequate. The terms inlet end 2 and outlet end 5 are used to indicateopposite ends 2 and 5 of the coiled tubing 1 is employed as the inletend 2.

The water line W may be attached to the coiled tubing 1 by anyconventional means, such as a fitting F or connector connected to asuitable hose. Alternatively, for example, a hose having an outsidediameter slightly larger than the inside diameter of the tubing 1 may beforced into the tubing 1 or a hose having an inside diameter slightlysmaller than the outside diameter of the tubing 1 may be clamped aboutthe outside diameter of the tubing 1.

It is essential that the coiled tubing 1 be substantially filled up withthe non-compressible liquid 3 prior to the application of thepressurized gas since this assures that the scarf 6 will be carried withthe liquid 3 out of the tubing 1.

After the coiled tubing 1 has been filled with the liquid 3, a plug 7 isinserted in at least the inlet end 2 of the tubing 1 as shown in FIG. 2.It is only essential in accordance with this invention that a plug 7 beinserted in the inlet end 2 since the function of the plug 7 is to forcethe cylinder of liquid 3 out of the coiled tubing 1; however, a secondplug 7' preferably is inserted in the exit end 5 of the tubing 1.

The purpose of the second plug 7 is to enable pressure to be built upagainst the first plug 7 and the column of liquid 3 so that the liquidmay be forced out under a substantial pressure, preferably, at least 200p.s.i. This is the most preferred approach for carrying out thisinvention and the one that works most successfully and consistently. Thesecond plug 7' may be held in place by any conventional means such as aclamp or more simply by the use of tape, or other like restraining means8.

A .gas under pressure is applied to the first plug 7 at the inlet end 2of the coiled tubing. The supply 10 of gas 9 under pressure is connectedto the inlet end 2 of the tubing 1 by any conventional means as, forexample, the use of a hydraulic chuck 11 which clamps about the tubing 1and which is connected to the gas supply 10. The gas supply 10, suitablyregulated by conventional means to provide the desired pressure, maycome from a compressor or from tanks of compressed gas as desired. Theparticular gas which may be employed is a matter of choice; however,preferably, air or nitrogen are used since they are the most economical.

An exemplary hydraulic chuck 11 is Model No. HC8B, manufactured by AirMo Hydraulics Inc. of Minneapolis, Minnesota, which is useful for oneinch diameter tubing 1. Other models are available which are adapted tobe used with the various sizes of tubing 1 which may be encountered. Thehydraulic chuck 11 is of conventional design and the one manufactured byAir Mo Hydraulics Inc. is merely set forth as being exemplary and is notmeant to be limitive of the invention.

FIG. 3 shows a typical plug 7 in accordance with this invention.Generally, the plugs 7 or 7' at the inlet end 2 and outlet end 5 of thetubing 1 are of the same construction. The structure shown in FIG. 3 ismerely exemplary and is not meant to be limitive of the invention. Theplug 7 shown therein has a cylindrical shape with an outside diametersubstantially equal to or smaller than the inside diameter of the coiledtubing 1 by as much as 0.050".

Other plug 7 shapes can be employed as desired. For example, balls havebeen used successfully; however, the shape shown in FIG. 3 is the mostpreferred and effecttive in accordance with this invention for tubing ofcircular cross section. For tubing of other than a circular crosssection, the plug 7 would have a substantially corresponding crosssection. The plug 7 shown is solid, however, plugs having a cup shapehave also been found to be useful. For example, plastic sleeve cups ofthe type used on electrical conduits have been employed successfullywhen the flat end was positioned opposite to the direction of fiow.Steel balls work well but are undesirable since they are dangerous asthey exit the coiled tubing 1 at high velocity.

The plug 7 may be formed of any desired material; however, the mosteffective material for the plug 7 has been found to be Elastacastpolyurethane, which is manufactured by Acushnet Company, Fort Worth,Texas. Elastacast has excellent chemical and abrasion resistance and istough and resilient. The Elasticast is available in the form of rods ofdesired cross section and plugs 7 or 7' of any desired length can be cutfrom the rods. The plugs 7 or 7 preferably range in length from about/2" to about 1'. The Elasticast has a degree of resiliency whichprovides a markedly improved wipping action when used in accordance withthis invention, namely, it has been found that the use of an Elastacastplug 7 provides a squeegee type wiping action as the plug is forcedthrough the tubing.

The gas pressure which is applied to the plug at the inlet end 2 of thetubing 1 to force it through the coil generally ranges up to 600 p.s.i.and preferably is from 350 to 500 p.s.i. Greater pressures up to theburst pressure of the tubing could be employed but are not deemed to benecessary.

Referring again to FIG. 2, it is seen that a gas pressure fitting 11which preferably is a hydraulic chuck is attached to the inlet end 2 ofthe coiled tube 1. A valve 12 in the line 13 between the high pressuregas supply 10 and the fitting 11 allows the gas to be turned on and 01T.These elements then comprise an exemplary means for applying the gasunder pressure to the plug 7 at the inlet end 2 of the tubing.

FIG. 4 shows the apparatus of this invention in operation. As shown inFIG. 4, the valve 12 in the gas line 13 has been opened and therestraining means 8 removed and the gas 9 under pressure has forced theplug 7 at the inlet end 2 to traverse the wraps 4 of the coiled tubing 1to almost the outlet end 5 of the tubing 1. The second plug 7 has beenblown out of the tubing 1 as shown. The liquid 3 flows out of the tubing1 as shown and the scarf 6 separates from the liquid because of itsgreater weight as it exits the tubing 1 and is easily collected forreuse as scrap.

When the process is carried to completion, the plug 7 would also exitthe tubing 1 in a manner similar to the plug 7 After the inlet end plug7 has exited from the tubing 1, the flow of gas may be continued throughthe tubing 1 to remove any liquid 3 which may have been retained. It hasbeen found, however, that the use of an Elastacast plug 7 by virtue ofits squeegee action provides a substantialy clean surface leaving littleor no liquid in the tubing.

This invention is applicable to coiled tubing 1 having a wide range ofoutside diameters and, preferably, to tubing 1 having a diameter of /2"to 3 /8 and, most preferably, to tubing having a diameter of %1 to 1%".The inside diameter of the tubing 1 may vary depending on tube wallthickness.

In accordance with this invention, it is possible to remove the scarf 6from coils 1 of very substantial length, preferably, up to 5,000 ft.long and, most preferably, up to 2,500 ft. long. Generally, the coilsrange from 1,000 to 3,000 ft. in length. This represents a markedimprovement over prior processes where the coiled tubing 1 has to be cutinto short lengths of a few hundred feet in order to be able to becleaned.

The diameter of the coils 1 will vary depending on the diameter of thetubing and the particularly coiling apparatus which has been employed.The process is preferably applicable to coils 1 having an outsidediameter of up to 200" and has found particular use with coils of adiameter of 36" to 100". The inside diameter of the coil shouldpreferably range from about 20" to about 190" and, preferably, from 20"t o 96".

The tubing preferably is formed of copper or copper base alloys,aluminum or aluminum base alloys, iron or iron base alloys, or nickel ornickel base alloys.

The substantially non-compressible liquid 3, may contain any desiredadditives such as, for example, corrosion inhibitors.

This invention may be embodied in other forms or carried out in otherways without departing from the spirit or essential characteristicsthereof. The present embodiment is therefore to be considered as in allrespects illustrative and not restrictive, the scope of the inventionbeing indicated by the appended claims, and all changes which comewithin the meaning and range of equivalency are intended to be embracedtherein.

What is claimed is:

1. A process for removing the internal scarf from within a coil oftubing having a plurality of wraps and inlet outlet ends comprising:

substantially filling up said tubing with a substantiallynon-compressible liquid; providing a first plug in said inlet end ofsaid tubing, of said plug having a diameter slightly less than orsubstantially the same as the inside diameter of said tubing, andcontacting said liquid; and applying a gas under pressure to said inletend of said tubing and against said plug so as to force said plug totraverse the wraps of said tubing and thereby force said liquid and saidscarf out of the outlet end of said tubing.

2. A process as in Claim 3 wherein intermediate said filling and saidgas application steps a second plug is provided in the outlet end ofsaid tubing; and wherein said second plug is restrained from beingforced out of said tubing during said gas application step until thepressure on said first plug has built up to at least 200 p.s.1.

3. A process as in Claim 2 wherein the length of said tubing in saidcoil is less than 5,000 ft. long.

4. A process as in Claim 3 wherein the length of said tubing in saidcoil is between 1,000 and 3,000 ft. long.

5. A process as in Claim 3 wherein said gas under pressure comprisesnitrogen.

6. A process as in claim 3 wherein said gas under pressure comprisesair.

7. A process as in Claim 5 wherein said substantially non-compressibleliquid comprises Water.

8. A process as in Claim 6 wherein said substantially non-compressibleliquid comprises water.

9. A process as in Claim 7 wherein said gas pressure comprises 350 to500 p.s.i.

10. A process as in Claim 8 wherein said gas pressure comprises 350 to500 p.s.i.

11. A process as in Claim 9 wherein after said first plug has exitedfrom said tubing the step of applying said gas under pressure iscontinued until substantially any residual amount of said liquidremaining in said tubing has been removed.

12. A process as in Claim 10 wherein after said first plug has exitedfrom said tubing the step of applying said gas under pressure iscontinued until substantially any residual amount of said liquidremaining in said tubing has been removed.

13. An apparatus for removing the internal scarf from within a coil oftubing having a plurality of wraps and inlet and outlet ends comprising:

means for substantially filling up said tubing with a substantiallynon-compressible liquid;

a first plug inserted in said inlet end of said tubing after the fillingof said tubing with said non-compressible liquid so as to contact saidliquid, said plug having a diameter slightly less than or substantiallythe same as the inside diameter of said tubing; and

means for applying a gas under pressure to said plug so as to force saidplug to traverse the wraps of said tubing and thereby force said liquidand said scarf out of the outlet end of said tubing.

14. An apparatus as in Claim 13 wherein said means for applying said gasto said plug comprises a supply of gas under pressure which is connectedto the inlet end of said tubing.

15. An apparatus as in Claim 14 wherein a valve is provided intermediatesaid gas supply and said inlet end of said tubing to enable the gasunder pressure to be turned on and 01f.

16. An apparatus as in Claim 14 wherein a second plug is provided in theoutlet end of said tubing and wherein a restraining means is providedfor preventing said second plug from being forced out of said tubingwhen said gas is applied until the pressure on said first plug has builtup to at least 200 p.s.i.

17. An apparatus as in Claim 16 wherein the pressure of said gas fromsaid supply comprises 350 to 500 p.s.i.

References Cited UNITED STATES PATENTS 1,807,457 5/1931 Weis --953,135,322 6/1964 Neugebauer 134-22 C 1,642,610 9/1927 Ingles 134-22 C3,349,212 10/1967 Morris 21959 3,216,858 11/1965 Bogdanowski 134-8MORRIS O. WOLK, Primary Examiner D. LOVERCHECK, Assistant Examiner US.Cl. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE 0F CORRECTION Patent No. 3,825,l l3 Dated July 23, 197

Inventor(s) Dennis E. Reilly It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

In Column 3, line 28, after the words "tubing 1'', insert the phrase andit is completely discretionary as to which end of the coiled tubing '\isIn Column 3, line 70, after the word "nitrogen", please delete the word"are" and insert in its place is In Column 5, corresponding to Claim 1,line 1 4, please 4 cancel the second occurrence of the word "of".

In Column 5, corresponding to Claim 2, line 52, after the word "Claim",please delete the number "3" and insert in its place l In Column 6,corresponding to Claim 13, line 25, after the word "filling", pleaseinsert the word up Signed and sealed this 27th day of May 1975.

(SEAL) Attest:

C. MARSHALL DANN RUTH 'C. MASON Commissioner of Patents AttestingOfficer and Trademarks FORM Po-1oso 1o-69, uscoMM-oc eoa'lemes 9 LLS,GOVERNMENT PRINTING OFFICE: I959 035'334

